A circle with circumference $16\pi$ has an arc with a $270^\circ$ central angle. What is the length of the arc? ${16\pi}$ ${270^\circ}$ $\color{#DF0030}{12\pi}$
The ratio between the arc's central angle $\theta$ and $360^\circ$ is equal to the ratio between the arc length $s$ and the circle's circumference $c$ $\dfrac{\theta}{360^\circ} = \dfrac{s}{c}$ $\dfrac{270^\circ}{360^\circ} = \dfrac{s}{16\pi}$ $\dfrac{3}{4} = \dfrac{s}{16\pi}$ $\dfrac{3}{4} \times 16\pi = s$ $12\pi = s$